Objective Curcumin can suppress the development of abdominal aortic aneurysms by inhibiting inammation. The objective of this study is to investigate the effect of curcumin on the expression of Bcl-2 and Bax during rat thoracic aortic aneurysm formation. Methods Thirty adult male Wistar rats were randomly divided into three groups: control group, aneurysmal group and curcumin group. The thoracic aortic aneurysm model induced by CaCl₂ was made, followed by daily oral gavage with 100 mg/kg curcumin or vehicle alone. The thoracic aortic segments were collected at 4 weeks after surgery. HE staining and orcein staining were used to observe the histological changes in the thoracic aorta. Immunohistochemistry and Western blotting were performed to detect the expressions of Bcl-2 and Bax in the wall of aneurysm. Results Curcumin significantly inhibited CaCl₂ -induced expansion of thoracic aorta, along with structural preservation of medial elastin fibers. Compared with the control group, the expression of Bax was higher, and the expression level of Bcl-2 was lower in the aneurysm group. Curcumin effectively reduced the expression of Bax, and increased Bcl-2 expression level in the aneurysm. Conclusion Our study shows that curcumin can promote the expression of Bcl-2 protein, inhibit the expression of Bax protein, and decrease the ratio of Bax/Bcl-2 in thoracic aortic aneurysms.